Color prints of improved brightness

ABSTRACT

COLOR PRINTS HAVING INCREASED BRIGHTNESS AND WITH WHITE PRINT BORDERS ARE PRODUCED BY THE INCLUSION OF AN OPTICAL BRIGHTENING AGENT IN THE IMAGE RECEIVING ELEMENT OF A DYE DEVELOPER DIFFUSION TRANSFER SYSTEM. THE BRIGHTENER IS PLACED INTERMEDIATE A SUPPORT LAYER AND A DYEMORDANT LAYER IN THE IMAGE RECEPTION ELEMENT.

United States Patent Dfice 3,592,645 COLOR PRINTS F IMPROVED BRIGHTNESS Walter J. Weyerts and Gladys L. Macllntyre, Rochester,

N.Y., assignors to Eastman Kodak Company, Rochester, N.Y. No Drawing. Filed Aug. 30, 1967, Ser. No. 664,257 Int. Cl. G03c 5/54, 1/60 US. Cl. 96-29D 16 Claims ABSTRACT OF THE DISCLOSURE Color prints having increased brightness and with whiter print borders are produced by the inclusion of an optical brightening agent in the image receiving element of a dye developer diffusion transfer system. The brightener is placed intermediate a support layer and a dyemordant layer in the image reception element.

The present invention relates to the art of photography. More particularly, this invention relates to the production of color prints of increased brightness and to novel photographic products for use in diffusion transfer systems utilizing dye developers.

Compounds which contain in the same molecule both the chromophoric system of a dye and a photographic silver halide developing moiety have been described in the photographic art as useful compounds in photographic elements for preparing color images by diffusion transfer processes. Such compounds are commonly called dye developers. Photographic elements containing such dye developers generally comprise a plurality of photosensitive silver halide emulsions wherein each of the emulsions is selectively sensitized to a different region of the spectrum. A dye developer is positioned contiguous to the silver halide in each of such emulsions, the dye developer being substantially complementary in color to the color of light recorded in the contiguous silver halide. Such a photoelement is processed with an alkaline composition.

The latent image is developed in the negative image areas with the dye developers, this development immobilizing the dye developers in such negative image areas. The dye developers in the unexposed areas diffuse to the surface imagewise and are transferred to a reception element or receiving sheet to form a positive multicolor print. Such color diffusion transfer processes are disclosed in US. Pats. 2,983,606; 3,146,102; 3,161,506; British Pat. 804,971, and French Pat. 1,313,767; as Well as elsewhere in the literature.

The print-receiving sheet that is employed in such diffusion transfer systems comprises a supporting layer, such as paper or coated paper, which may carry thereon in the following order: (1) an acid layer for neutralization of excess alkali; (2) a spacer layer; and (3) a dye-mordant layer. A serious problem in the production of high quality color prints is that the processing cycle that is employed in diffusion transfer systems results in a color print that has an off-White to yellow stained border. This defect is highly undesirable, since it materially reduces the apparent color saturation and brightness of thefinal color print.

Accordingly, it is an object of this invention to provide novel photographic products of increased brightness and color saturation.

A further object of the invention is to provide novel color prints of increased brightness and whiter print borders in dye diffusion transfer systems.

Another object of the invention is to provide a novel process for the production of color prints of increased brightness and color saturation from a psychological standpoint.

3,592,645 Patented July 13, 1971 These and other objects are achieved in accordance with the present invention whereby a reception element for use in a dye developer diffusion process is provided Which comprises a support layer having superposed thereon in order at least one layer containing an optical brightening agent, and a dye-mordant layer.

It has been found that the color saturation and brightness of color prints that are produced in a dye diffusion transfer system may be materially increased by the employment of a reception element which comprises a support having superposed thereon an acid layer, a spacer layer and a dye-mordant layer, with an optical brightening agent being provided in at least one of the layers intermediate the dye-mordant layer and the support. The border of the resultant color print is whiter, and the brightness of the print is increased to a great extent. The off-white to yellow staining that resulted in the borders of the prints produced by prior diffusion transfer systems is eliminated from the prints of the present invention.

The positioning of the optical brightening agent in the receiving element of the present invention is vital to the success of the invention. Thus, the brightening agent may be dispersed in the spacer layer and/ or in the acid layer. Preferably, the brightening agent is placed in the spacer layer. However, the optical brightening agent should not be utilized in or over the dye-mordant layer since its inherent ability to fluoresce will tend to lower the color saturation of the dyes and will distort the black and neutral colors. Accordingly, the optical brightening agents of the present invention are suitably provided in a layer intermediate the support layer and the dye-mordant layer, and preferably in the spacer layer.

The term optical brightening agent as used herein is intended to include those colorless or substantially colorless organic compounds which absorb ultraviolet light from sunlight or fluorescent light and emit the absorbed energy as visible blue or blue-green light. Thus, such compounds contain fluorescent chromophores in contradistinction to dyes, which contain colored chromophores.

Suitable optical brightening agents include, for example, those brighteners selected from the following general classes of organic compounds: triazine-stilbenes, coumarins, anthracenes, terphenyls tetraphenylbutadienes, quinoxalins, and the like. These classes of compounds are conventional for use as fluorescent agents and as optical bleaching agents. For example, suitable triazine-stilbene optical brightening agents are described in US. Pat. 2,933,390 and have the following general formula:

wherein R R R and R each represents a hydrogen atom, or a substituent group, such as hydroxyl aryloxyl (e.g., phenoxyl, o-toloxyl, p-sulfophenoxyl, etc.), alkoxyl (e.g., methoxyl ethoxyl, etc.) a halogen atom (e.g., chlorine, bromine, etc.), a heterocyclic radical (e.g., morpholinyl piperidyl, etc.), an alkylthio group (e.g., methylthio, ethylthio, etc.), an arylthio group (e.g., phenylthio, tolylthio, etc.), a heterocyclylthio group (e.g., benzothiazylthio, etc.), an amino group, an alkylamino group (e.g. methylamino, ethylamino, propylamino, dimethylamino, diethylamino, dodecylamino, cyclahexylamino, B-hydroxyethylamino, di-[i-hydroxyethylamino, ,B-sulfoethylamino, etc.), an arylamino group (e.g., anilino, 0-, m-, and p-sulfonanilino o-, m, and p-chloroanilino, o-, m-, and p-anisylamino, o-, m-, and p-toludino, o-, m-, and p-carboxyanilino, hydroxyanilino, sulfonaphthylamino, o-, m-, and p-arninoanilino, p-acetamidoanilino, etc.), etc., and R 3 and R each represents a hydrogen atom or a water-solubilizing group, such as sulfo, carboxyl, etc. (as well as alkali metal or amino salts of such groups).

Examples of these compounds include 4 4-bis[4-(3'- sulfonanilino) 6 amino-s-triazin 2 ylamino]-stilbene- 2,2 disulfonic acid; 4,4-bis[4,6-di(/S-hydroxyethylamino)-s-triazin-2-ylamino]-stilbene-2,2-disulfonic acid, and the like.

Compounds of the above type are also described in one or more of the following patents: U.S. 2,171,427; 2,473,- 475; 2,595,030; 2,660,578; British Pats. 595,065; 623,849; 624,051; 624,052; 678,291; 681,642; 705,406. Additionally, compounds suitable for use in the reception element of the present invention are commercially available under such trade names as Tinopal [SP, WR, SFG, BV277, 2B, GS, NG], Leucophor B, Calcofluor White MR Blancofor SC, Hitamine [BSP, N, 501., 6T6], and the like.

Suitable coumarin optical brightening agents are, for example, the 3-phenyl-7-ureidocoumarins described in British Patent 786,234 and which have the general formula:

wherein R represents the radical of ammonia or of an organic primary or secondary amine, and R represents a phenyl radical, a halogen radical, or an alkyl substituted phenyl radical.

Examples of these compounds include: N -[3-(p-methyl phenyl)-coumarinyl-(7)]-urea; N-propyl-N -[3-phenyl-coumarinyl-(7) ]-urea; N 3 su1phoethyl-N -3-phenyl coumarinyl-(7)-urea and the like. These compounds are commercially available under such trade names as Tiropal SFG (Geigy).

Similarly, anthracenes, terphenyls, tetraphenylbutadicues and quinoxalins are conventional optical brightening agents and are well known in the art.

The concentration of the optical brightening agent may be varied over a wide range. Suitable concentrations include those in the range of between about 0.25 and about 10 milligrams of the optical brightening agent per square foot of reception element surface area, preferably between about 1.0 and about 5.0 milligrams per square foot. Higher concentrations of the brightening agent may be employed, but it is both unnecessary and impractical to do so.

A wide variety of photographic supports may be used in the reception element of the present invention. Suitable supports include a paper support, a polyethylene coated paper support, a transparent film, a white pigmented cellulose ester support such as cellulose acetate film, and the like. The support may be provided with an optical brightening agent, if desired.

The acid-containing sublayer contains nonditfusible or immobilized acid-substituted or acid-yielding ballasted monomeric acid or polymeric acid compounds capable of reacting with alkaline materials or polymeric bases, or it can contain compounds having substituents capable of trapping basic reactants. Suitable monomeric acids are carboxylic acids typically containing at least 16 carbon atoms such as stearic acid and palmitic acid. Polymeric acidic compounds are referred in the acid layer of the image receiving elements used in the invention. Among the suitable polymers are water-soluble carboxylated polymers whose sodium and/or potassium salts are watersoluble. Alternatively, polymers can be used which initially contain acid anhydride groups which are transformed, during processing, to free carboxyl groups. Polymeric acids used in the acid sublayer can be derivatives of cellulose or vinyl polymers, as well as acids of other polymeric compounds. Examples of typical polymeric acids are: di-

basic half esters of derivatives of cellulose containing free carboxyl groups, e.g., cellulose acetate-hydrogen phthalate; cellulose acetate-hydrogen glutarate; cellulose acetate-hydrogen succinate; ethyl cellulose-hydrogen succinate; ethyl cellulose acetate-hydrogen succinate, hydrogen phthalate; etherand ester-derivatives of cellulose which are modified with sulfoanhydrides, e.g., with o-sulfobenzoic acid anhydride, polystyrylsulfonic acid, carboxy-methyl cellulose, polyvinyl-hydrogen phthalate polyvinyl-acetate-hydrogen phthalate, polyacrylic acid, acetals of polyvinylalcohol and carboxy or sulfo-substituted aldehydes, e.g., o-, m-, or p-benzaldehyde-sulfonic acid or -carbonic acid, partial ester of ethylene-maleic acid anhydride mixed polymers, partial ester of methylvinylether-maleic acid anhydride mixed polymers.

The function of the acid sublayer in the receiving element is to terminate development and to stabilize the final print by reacting with, and lowering the pH of, the alkaline developer composition used for processing the light-sensitive photographic element from which the dyes diifuse as a function of exposure and development.

A spacer layer is suitably provided between the acid layer and the dye-mordanting layer. The spacer layer controls the rate of diffusion of components of the alkaline developing composition into the acid layer. The spacer layer allows suflicient time for complete development of the exposed photosensitive element, as well as time for complete transfer of dye from the photosensitive element into the dye-receiving element and for adequate formation of the color image in the dye receptive mordanted layer 0 the receiving element. Typically, the spacer layer is from 3 to 25, and preferably 8 to 15 microns, in thickness. The spacer layer may comprise polyvinyl acetate, polyvinyl alcohol, gelatin and the like. It can contain a white pigment, as described in Beavers et al. US. patent application Ser. No. 557,511, filed Jan. 14, 1966, and now US. Pat. 3,445,228. It may also contain, if desired, conventional addenda, e.g., coating acids, hardeners, etc.

The mordant-containing dye image receiving layers of the receiving sheets used in the process of the invention are alkali permeable and can contain any of the conventional mordant materials for dyes. The mordant layer can contain such mordants as polymers of mino guanidine derivatives of vinyl methyl ketone such as described in the Minsk US. Pat. 2,882,156, granted Apr. 14, 1959. Other suitable mordants include the 2-vinyl pyridine polymer metho-p-toluene sulfonate and similar compounds described in Sprague et al. US. Pat. 2,484,430, granted Oct. 11, 1949 and cetyl trimethylammonium bromide, etc. Particularly effective mordanting compositions are described in copending applicatons of Whitmore U.S. Ser. No. 211,- 095, filed July 19, 1962, now US. Pat. 3,271,148 and Bush Ser. No. 211,094, filed July 19, 1962 and now US. Pat. 3,271,147. The mordanting compositions described in the Whitmore application comprise at least one hydrophilic organic colloid containing a finely-divided uniform dispersion of droplets or globules of a high-boiling, water-immiscible organic solvent in which is dissolved a high concentration of a cationic, nonpolymeric, organic dyemordanting compound for acid dyes. The mordanting compositions described in the Bush application comprise at least one hydrophilic organic colloid containing a finelydivided, uniform dispersion of particles of a salt of an organic acidic composition containing free acid moieties and a cationic, nonpolymeric, organic dye-mordanting compound for acid dyes. Useful cationic or basic organic dyemordanting compounds for dyes include quaternary ammonium and phosphonium, and ternary sulfonium compounds in which there is linked to the N, P or S onium atom at least one hydrophobic ballast group such as longchain alkyl or substituted alkyl groups.

The optical brightening agent may be incorporated into the intermediate layer, e.g., the acid layer or spacer layer of the reception element, in any suitable manner. For example, if the brightener is water-soluble, it may be incorporated into the intermediate layer in the form of an aqueous solution of the brightening agent. The waterinsoluble optical brightening agents are preferred for the purposes of the present invention. Thus, the water-insoluble or slightly soluble brightening agent may be incorporated into the intermediate layer in an organic solvent, such as methanol, ethanol, pyridine and the like. However, it is preferred to employ a latex dispersion in which the brightener is associated with Latex particles for incorporating the brightener into an intermediate layer.

A very desirable means of providing a latex dispersion of the water-insoluble optical brighening agent is described in US. patent application Ser. No. 476,675 to Van Campen filed on Aug. 2, 1965 and now abandoned, the disclosure of which is hereby incorporated by reference. Thus, the water-insoluble brightener is preferably dissolved in a water-immiscible solvent, e.g., ethyl acetate, chloroform, etc., along with a vinyl resin, such as a polyalkyl acrylate, polyalkyl methacrylate, polyvinyl acetal, copoly[alkyl acrylate, alkyl methacrylate1polymer and the like. The resulting solution is then emulsified in an aqueous solution of a hydrophilic film-forming binder, such as gelatin, copoly[ethyl acrylate, acrylic acid]resin, and the like. Next, the emulsion is set and dried by evaporation to remove the solvent and water. The dried material may then be reconstituted as a coating fluid by soaking in water and stirring mechanically. The resultant fluid may then be coated as desired after addition of the acid polymer in the case of an acid layer; or a spacer material, such as polyvinyl alcohol, in the case of a spacer layer; or as it.

In accordance with usual practice, the positioning of the dye image-forming units of the photographic element, which may be used in the invention may be varied. In three-color systems, it is preferred to utilize the cyan dye image-forming unit most proximate to the support, the yellow dye-forming unit furthest from the support, and the magneta dye image-forming unit between the cyan and yellow dye image-forming units. It is also preferred to utilize the dye developers in the respective dye image-forming units in a separate underlying layer contiguous to the silver halide emulsion layer. Likewise, it is preferred to utilize in each dye image-forming unit a dye developer that is substantally complementary in color to the color of light recorded by the silver halide in the unit.

The dye developers which may be used in the invention are widely described in the literature. Such compounds function as a silver halide developing agent and as a dye in photographic diffusion transfer systems. Dye developers are characterized as being relatively nondiffusible in colloid layers such as the hydrophilic organic colloids used in photographic emulsions at neutral pH, but diffusible in such emulsions in the presence of alkaline processing solutions.

In general, dye developers are characterizd as having both a chromophoric or dye moiety and at least one moiety having a silver halide developing function. Typical of the useful dye developers are those wherein the chromophoric moiety is an azo or anthraquinone dye moiety and the silver halide developing moiety is a benzenoid moiety such as hydroquinyl moiety.

[Representative dye developers of use in the sensitive elements of the invention have the general formula in which M is an aromatic or heterocyclic ring or ring system such as a benzene, naphthalene, tetralin anthracene, anthraquinone, pyrazole, quinoline, etc., ring and may also be substituted, as by hydroxyl amino, keto, nitro, alkoxy, aryloxy, acyl, alkylamido, arylamido alkyl, aryl, carboxamido, sulfoamido, carboxyl or sulfo groups. D represents a silver halide developing agent moiety imparting the developing agent function to the dye developer such as a hydroquinolyl group which may be substituted with amino, alkylamino, alkyl, hydroxyl, alkoxyl or halogen groups.

Useful dye developers are those disclosed in Australian Pat. 220,279, accepted Dec. 17, 1958 and German Pat. 1,036,640, Aug. 14, 1958, which include:

(magenta dye developer) 2-[p-(2,5'-dihydroxyphenethyl)-phenylazo]-4-methoxyl-naphthol. 2- [p-(2',5'-dihydroxyphenethyl -phenylazo] -4-ethoxyl-naphthol. 2-[p-(2,5-dihydroxyphenethyl)-phenylazo] -4-npropoxy-l-naphthol.

l-phenyl-3-N-n-butyl-carboxamido-4-[p-(2,5'-dihydroxyphenethyl -phenylazo] -5-pyrazolone.

l-phenyl-3 -N-n-hexylcarboxamido-4- [p-2',5 -dihydroxyphenethyl -phenylazo -5-pyrazolone.

Another class of suitable dye developers disclosed by British Pat. 804,971, Nov. 26, 1958, and British Pat. 804,973, Nov. 26, 1958, are as follows:

1-4-bis- (2',5 -dihydroxyanilino -anthraquinone,

1,S-bis(2',5'-dihydroxyanilino)-4,8-dihydroxyanthraquinone,

1,4-biS [B-3,4-dihydroxyphenyl -ethylamino] -anthraquinone,

NH CPI-CH2" 0 ll OH OH H l o NHOHCH2 I OH (cyan dye developer) 1,4-bis [3-(2',5-dihydroxyphenyl) -isopropylarnino] anthraquinone, 1,4-bis [;8-(2',5 '-dihydroxyphenyl -ethylamino] -anthraqumone, 1-chloro-4-[18-(2' 5 '-dihydroxyphenyl -ethyla'mino] anthraquinone.

Additional dye developers are disclosed in US. Pats. 3,146,102, 3,161,506, Belgium Pat. 554,935, British Pats. 804,971, 804,973 and French Pat. 1,168,292.

In the photographic element of the invention, the dye developers are preferably incorporated in hydrophilic organic colloidal vehicles or carriers comprising the layers of the photographic element dissolved in highboiling or crystalloidal solvents and dispersed in finelydivided droplets. In preparing such dispersions of dye developers, high-boiling or substantially water-immiscible organic liquids having boiling points above about 175 C. may be utilized. The high-boiling solvent may be used alone in dissolving the dye developer and in forming the dispersion or it can be mixed with a low-boiling organic solvent (e.g. boiling at least C. below the boiling point of the higher boiling solvent), or a water-soluble organic solvent, as an auxiliary solvent to facilitate solution of the dye developer.

A preferred range of proportions of high-boiling solvent to auxiliary is 1/1 to 1/ 10 on a weight basis. Such auxiliary solvents can be readily removed from the highboiling solvent, for example, by air-drying a chilled, noodled dispersion or by continuous water Washing. Several of such high-boiling solvents and auxiliary solvents utilized for incorporating dye developers are described in (French Pat. 1,313,765. The dye developers may also be incorporated into vehicles soluble in organic solvents which are also solvents for the dye developer. Likewise, other incorporating techniques for the dye developer such as ball-milling can be utilized.

The photographic element may desirably contain auxiliary developing agents such as colorless substantially water-insoluble hydroquinone derivatives such as are disclosed in French Pat. 1,313,086. Such auxiliary developing agents may be incorporated in the silver halide emulsion layers, in overcoat layers, in interlayers or in other layers of the element.

The silver halide emulsions utilized in preparing the photographic element of the invention may be any of the conventional negative-type, developing-out emulsions. Typical suitable silver halides include silver chloride, silver bromide, silver bromoiodide, silver chloroiodide, silver chlorobromoiodide and the like. Mixtures of more than one of such silver halides can also be utilized. In preparing such silver halide emulsions, a wide variety of hydrophilic organic colloids can be utilized as the vehicle or carrier. It is preferred to utilize gelatin as the hydrophilic colloid or carrier material although such material as polyvinyl alcohol and its water-soluble derivatives and copolymers, Water-soluble copolymers such as polyacrylamide, immidized polyacrylamide, etc., and other water-soluble film-forming materials that form water-permeable coats such as colloidal albumin, watersoluble cellulose derivatives, etc., can be utilized in preparing the present photographic elements. Compatible mixtures of two or more of such colloids can also be utilized.

In the present photographic products, the dye developers are disposed integral with the element and contiguous to silver halide of each of the light-sensitive silver halide emulsion layers. Such dye developers can be incorporated directly in the light-sensitive silver halide emulsion layers or in separate layers contiguous to the layers containing the silver halide. The present photographic elements contain at least one dye image-forming unit, each unit comprising a light-sensitive silver halide emulsion and a dye developer contiguous to silver halide in the unit. Each dye image-forming unit is preferably spectrally sensitized to record light that is substantially complementary to the color of the dye developer in the unit.

The processing compositions or activators used to initiate development of the exposed light-sensitive elements of the invention are strongly alkaline. Such processing compositions generally have a pH of at least about 12 or contain at least .01 N hydroxyl ion. Alkali metal hydroxides, such as sodium hydroxide, and sodium carbonate, are advantageously used in the composition for imparting such high alkalinity. However, volatile amines such as diethyl amine can also be used, such amines having the advantage of being volatilized from the prints to leave no residue of alkali. Such processing compositions are generally aqueous liquids or solutions, and when utilized in rupturable pods for in-camera processing, generally contain thickening agents such as hydroxyethyl cellulose or carboxymethyl cellulose. Onium compounds such as are disclosed in US. Pats. 3,146,102, 3,161,506, French Pat. 1,313,767 and British Pat. 938,865 are preferably utilized in the alkaline processing composition.

Camera apparatus of the type useful for exposing and processing the sensitive elements of the invention have been described, for example, in US. Pat. 2,435,717. The processing of the subject photographic elements can also be effected outside of camera apparatus by imbiding either the receiving element or the negative element or both in the alkaline processing composition, and thereafter sandwiching together the two elements to allow the dye developer images to diffuse to the receiving element.

The following examples will serve to illustrate the present invention.

EXAMPLE 1 A photographic element is prepared by coating successively the following layers on a subbed cellulose acetate film support:

(1) Cyan dye developer layer An aqueous gelatin solution containing the cyan dye developer, 5,8 dihydroxy l,4-bis[(fl-hydroquinonyl-amethyl)-ethylamino]anthraquinone, dissolved in a mixture of N-n-butyl-acetanilide, 4 methyl cyclohexanone and dispersing agent Alkanol B, is passed through a colloid mill several times and is coated and dried so as to volatilize the 4-methyl cyclohexanone.

(2) Red-sensitive emulsion layer A gelatino-silver bromoiodide emulsion layer sensitized to the red region of the spectrum is coated upon the cyan dye developer layer.

(3) Interlayer A coating of gelatin is placed over the red-sensitive emulsion layer.

(4) Magenta dye developer layer An aqueous gelatin solution containing the magenta dye developer, 2-[p(2',5' dihydroxyphenethyl) phenylazo]-4-n-propoxy-1-naphthol is dissolved in a mixture of cyclohexanone-N-n-butyl-acetanilide and Alkanol B, and the mixture is passed through a colloid mill several times, coated on the interlayer and dried to volatilize the cyclohexanone.

(5) Green-sensitive emulsion layer A green-sensitive emulsion layer comprising a coating of gelatino-silver bromoiodide emulsion is coated upon the magenta layer.

(6) Interlayer A coating of gelatin is placed over the green-sensitive layer.

(7) Yellow dye developer layer An aqueous gelatin solution containing the yellow dye developer, 1 phenyl 3 N-n-hexylcarboxarnido-4-[p- (2',5' dihydroxyphenethyl)phenylazo] 5-pyrazolone, is dissolved in a mixture of ditetrahydrofurfuryl adipate, ethylene glycol monobenzyl ether, and Alkanol B, and the mixture is passed through a colloid mill several times. The resulting dispersion is chilled to set it, washed to remove ethylene glycol monobenzyl ether and is COalCtl upon the second interlayer and dried.

(8) Blue-sensitive emulsion layer A blue-sensitive bromoiodide emulsion is coated on the yellow dye developer layer.

(9) Overcoat layer A gelatin coating containing dispersed therein colorless auxiliary dye developer 4 methylphenylhydroquinone is coated over the blue-sensitive emulsion layer.

EXAMPLE 2 A receiving sheet is prepared as follows:

Acid layer Twenty-five grams of a copolymer formed of butyl Dye mordant layer Six and one-quarter grams of a 10 percent solution of polyvinyl alcohol and 0.05 milliliter of isooctyl phenyl polyethoxy ethanol are added to 6.25 grams of a poly-4- vinylpyridine solution in acetic acid. The melt is made up to 25 grams with distilled Water and is coated over the spacer layer at a Wet thickness of 0.006 inch.

EXAMPLE 4 A receiving sheet identical to that of Example 3 is produced, except that 0.0088 gram of the brightener is added to the acid layer to yield a final coverage of 4 milligrams of the brightener per square foot.

acrylate (60%) and acrylic acid (40%) are dissolved in EXAMPLE 5 50 ml. of denatured ethanol. One gram of resorcinol bi- Each f three Samples f h film of Example 1 are glycidyl ether in 5.0 milliliters of ethanol is added to the posed under a step tablet through red, green and blue copolymer and suflicient ethanol is added to make a total filt and are wetted h an aqueous activator of 100 grams of the melt. The resulting mixture isv coated prising: onto a waterproofed paper support in the amount of 25 percent cc. per square foot, which is suificient to yield 2.5 grams Hydroxyethyl cellulose 0f t e a d resin P31 square foot of the pp (Hercules type 250 high viscosity) 3,5 spacer layer Sodium hYdIOXide 4.5 Benzotriazole 2.0 Eight grams of a 55 per p y y acetate latex 1 phenethy1 2-pic ,1inium bromide 21) dispersion is added to 12.5 grams of a 10 percent polyvinyl alcohol solution. Sufiicient water is added to yield While in contact with the receiving sheets of Examples 2, a total of 25.0 grams of the melt which is then coated 3 and 4, respectively. The cyan, magenta and yellow dye over the acid layer at a wet thickness of 0.004 inch. developer images transfer from the undeveloped regions D d lit 1a er to the receivlng sheet in each case. A transfer tlme of one ye mm a y minute and a roller gap of 0.0044 inch (corresponding to Twelve and one-half grams of a 10 percent polyvinyl the thickness of the activator layer) is employed in each alcohol solution, 0.5 milliliter of acetic acid, 0.1 milliliter ca e, of isooctyl phenyl polyethoxy ethanol, and 0.05 gram of The resultant color prints are tested for density, reflect- 1-phenyl-S-mercaptotetrazole are added to 1.25 grams of ance and relative radiance. The results are set forth below:

TABLE 1 Print Dan. 1).... (neutral scale) (neutral scale) Percent reflectance 1 Relative radiance 1 Red Green Blue Red Green Blue 400 m 40511111 410Il1p. 410 m 420m 430 m Example N0.:

1 Obtained from raw stock as coated, Le without transferred dyes. poly-4-vinyl pyridine in 25 milliliters of distilled water. EXAMPLE 6 The melt is made up to a total of grams with distilled water and is coated over the spacer layer at a wet thickness of 0.006 inch.

EXAMPLE 3 A receiving sheet similar to that of the previous example but containing an optical brightening agent in the acid layer is made as follows:

Acid layer Three grams of resorcinol biglycidyl ether dissolved in 20 milliliters of ethyl alcohol are added to 50 grams of a copolymer of butyl acrylate (60%) and acrylic acid (40%) in 20 milliliters of ethanol. Sufiicient ethanol is then added to produce 250 grams of the melt. The optical brightener N-(fl-dimethylaminoethyl) N [El-phenylcoumarinyl-(7)]urea (see Example 3 of British Pat. 786,234) in an amount of 0.0044 "gram is added to 25 grams of the melt. The melt is then coated on a waterresistant paper support to yield a coverage of 2 milligrams of the optical brightener per square foot.

Spacer layer Eight grams of a percent polyvinyl acetate latex and 0.05 gram of 1-phenyl-5-mercaptotetrazole is admixed with 12.5 grams of a 10 percent polyvinyl alcohol solution. Distilled water is added to make up a total of 25 grams of the melt which is coated over the acid layer at a wet thickness of 0.004 inch.

A receiving sheet is produced having an acid layer and a dye-mordant layer identical to that of Example 2. However, an optical brightener is incorporated into the spacer layer as follows:

Spacer layer Eight grams of a 55 percent polyvinyl acetate latex and 2.25 grams of an alkyl acrylate polymer latex (9.2 percent solids) containing 2.6 percent of the brightener N (B dimethylaminoethyl)-N-[3-phenyl-coumarinyl- (7)] urea, is added to 12.5 grams of a 10 percent polyvinyl alcohol solution. The melt is made up to 31 grams with distilled water and is coated at a wet thickness of 0.004 inch to yield 1.5 milligrams of the brightener per square foot.

This receiving sheet is processed as in Example 5 with the negative of Example 1. For comparative purposes, the relative radiance of the receiving sheet is compared with that of Example 2. The results are as follows:

TABLE 2 Relative radiance The negative of Example 1 and receiving sheet of Example 2 are processed as before, except that the negative is completely flashed before processing and transfer in order to determine the effect of processing conditions on the receiver sheet in the absence of a color transfer image. EXAMPLE 8 For comparative purposes, a receiving sheet having the acid and dye-mordant layers of Example 2 and the following spacer layer is produced:

Spacer layer This layer is identical to that of Example 6, with the exception that 4.5 grams of the alkyl acrylate latex dispersion is employed so as to yield an optical brightener coverage of 3.2 milligrams per square foot.

This receiving sheet is processed using the same nega- (b) aspacer layer, and

(c) a mordant-containing dye image-receiving layer, said photosensitive element and said dye developer reception element being capable of being superposed on each other, said container being so positioned as to be capable, upon being ruptured, of releasing said processing solution for application to said superposed photographic element and reception element, the improvement which comprises providing an organic optical brightening agent in at least one of the layers intermediate the support and the dye image-receiving layer.

9. The product of claim 8 wherein the brightening agent is provided in said acidifying layer.

10. The product of claim 8 wherein the brightening tive and processing conditions as in the previous ex- 15 agent is provided in said spacer layer. amples, except that the negative is completely flashed, 11. In a process for the production of a color print in E a le 7, of increased brightness WhlCh comprises processing a The relative radiance values for th prints f Exphotographic element comprismg light-sensitive silver amples 7 and 8 are set forth below: halide emulsion layers sensitive to light of different regions TABLE 3 Relative radiance 410 my. 420 mp. 430 my 440 mp. 450 my. 460 mu 470 mp 480 mp 490 m 500 mp. 600 my. 700 m i ig i jif 52 54. 0 66. o 51. 5 58.5 69. 0 60. s 61. 5 62.0 63. 0 68. 5 so. 5 s 55 60. 0 62. 0 62. 5 62. 5 63. 0 63. 5 64. 0 64. 5 64. 5 72. 5 s2. 0

From the foregoing data, it may be seen that the of the spectrum, and a dye developer, which is both a color prints provided by the present invention are of increased brightness and improved density and represent an important advance in dye developer diffusion transfer systems.

The invention has been described in considerable detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. In an image-receiving element for use in a dye developer diffusion transfer process, which comprises a support having superposed thereon in order:

(a) an acidifying layer,

(b) a spacer layer, and

(c) a mordant-containing dye image-receiving layer, the improvement comprising employing an organic optical brightening agent in at least one of the layers intermediate the support and the dye image-receiving layer.

2. The element of claim 1 wherein said organic optical brightening agent is provided in said acidifying layer.

3. The element of claim 1 wherein said organic optical brightening agent is provided in said spacer layer.

4. The element of claim 1 wherein said optical brightening agent is provided at a concentration in the range of between about 0.25 and about 10 milligrams per square foot.

5. The element of claim 1 wherein the optical brightening agent is a Water-insoluble triazine-stilbene compound.

6. The element of claim 1 wherein the optical brightening agent is a coumarin.

7. The element of claim 1 wherein the optical brightening agent is a 3-phenyl-7-ureido-coumarin.

8. In a photographic product composed of a photosensitive element comprising light-sensitive silver halide emulsion layers sensitive to different regions of the spectrum, and a dye developer which is both a silver halide developing agent and a dye, contiguous to the silver halide of said silver halide emulsion layers, a rupturable container containing an aqueous alkaline processing solution, a dye developer reception element comprising a support having superposed thereon in order:

(a) an acidifying layer,

silver halide developing agent and dye, contiguous to the silver halide of said silver halide emulsion layers, said processing being effected by treating said photographic element with an alkaline solution, developing latent images in the regions of exposure of said silver halide emulsion layers and thereby immobilizing each said dye developer in said regions of exposure, each said dye developer in undeveloped regions diffusing imagewise in register to a dye developer reception element which comprises a support having superposed thereonin order:

(a) an acidifying layer,

(b) aspacer layer, and

(c) a mordant-containing dye image-receiving layer, the improvementwhich comprises providing an organic optical brightening agent in at least one of the layers intermediate the support and the dye image-receiving layer.

12. The process of claim 11 wherein said brightening agent is provided in said acidifying layer.

13. The process of claim 11 wherein said brightening agent is provided in said spacer layer.

14. The process of claim 11 wherein the optical brightening agent is a water-insoluble triazine-stilbene compound.

15. The process of claim 11 wherein the optical brightening agent is a coumarin.

16. The process of claim 11 wherein the optical brightening agent is a 3-phenyl-7-ureido coumarin.

References Cited UNITED STATES PATENTS 2,584,030 1/1952 Land 9629 3,362,819 1/1968 Land 963 3,460,942 8/1969 Rogers 9629 3,253,915 5/1966 Weyerts et a1. 963 3,269,840 8/1966 Pattijn et a1. 9682 3,359,102 12/1967 Pattijn et al. 96l.8 3,445,228 5/1969 Beavers et al. 963

NORMAN G. T ORCHIN, Primary Examiner A. T. SURO PICO, Assistant Examiner U.S. Cl. X.R. 963, 82, 76C 

